1. Field of the Invention
This invention relates to a radiation image recording and read-out apparatus for recording a radiation image on a stimulable phosphor sheet, exposing the stimulable phosphor sheet to stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, detecting the emitted light to read out the radiation image, and converting the emitted light into electric signals. This invention particularly relates to a radiation image recording and read-out apparatus which is small as a whole.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. No. 4,258,264 and Japanese Unexamined Patent Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter refferred to as a stimulable phosphor sheet) is first exposed to a radiation passing through an object such as the human body to have a radiation image of the object stored thereon, and is then two dimensionally scanned by stimulating rays such as a laser beam which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted to electric image signals by a photodetector, and the radiation image of the object is reproduced as a visible image by us of the image signals on a recording medium such as a photographic film, a display device such as a cathode ray tube (CRT), or the like.
The radiation image recording and reproducing system using a stimulable phosphor sheet is advantageous over conventional radiography using a silver halide photographic material in that the image can be recorded over a very wide range (latitude) of radiation exposure. More specifically, since the amount of light emitted upon stimulation after the radiation energy is stored on the stimulable phosphor sheet varies over a wide range in proportion to the amount of said stored energy, it is possible to obtain an image having desirable density regardless of the amount of exposure of the stimulable phosphor sheet to the radiation, by reading out the emitted light with an appropriate read-out gain and converting it into electric signals to reproduce a visible image on a recording medium or a display device.
In the aforesaid radiation image recording and reproducing system, the stimulable phosphor sheet is used to temporarily store the radiation image in order to reproduce the final visible image therefrom on a final recording medium. For economical reasons, therefore, it is desirable that the stimulable phosphor sheet be used repeatedly.
Accordingly, the applicant proposed in, for example, Japanese Unexamined Patent Publication No. 58(1983)-200269, a radiation image recording and read-out apparatus which enables efficient circulation and reuse of the stimulable phosphor.
The proposed radiation image recording and read-out apparatus comprises, built in a single apparatus:
(a) a supporting material, PA1 (b) at least one recording material fixed on said supporting material and comprised of a stimulable phosphor layer capable of storing a radiation image, PA1 (c) an image recording section for exposing said recording material to a radiation passing through an object to have a radiation image of the object stored on said recording material, PA1 (d) an image read-out section provided with a stimulating ray source for emitting stimulating rays for scanning said recording material carrying said radiation image stored thereon, and a photoelectric read-out means for obtaining electric image signals by reading out light emitted by said recording material scanned and stimulated with the stimulating rays, PA1 (e) a means for circulating said recording material on said supporting material with respect to said image read-out section for enabling reuse of said recording material by repeatedly moving said supporting material and said image read-out section with respect to each other, and PA1 (f) an erasing section for eliminating the radiation energy remaining on said recording material prior to image recording on said recording material after the radiation image is read out therefrom at said image read-out section, PA1 (i) a stimulable phosphor sheet, PA1 (ii) an image recording means for exposing said stimulable phosphor sheet to a radiation passing through an object, thereby to store a radiation image of said object on said stimulable phosphor sheet, PA1 (iii) a read-out and erasing unit comprising, formed integrally with each other into a unit: (a) an image read-out means provided with a stimulating ray scanning means for scanning said stimulable phosphor sheet carrying said radiation image stored thereon by stimulating rays deflected by a light deflector, and a photoelectric read-out means for photoelectrically detecting light emitted by said stimulable phosphor sheet in proportion to the stored radiation energy at a position of scanning by said stimulating rays, thereby to read out said radiation image, and (b) an erasing means for carrying out erasing by releasing radiation energy remaining on said stimulable phosphor sheet on which the image read-out has been finished, and PA1 (iv) a unit movement means for reciprocally moving said read-out and erasing unit in a direction approximately normal to the direction of scanning of said stimulating rays, PA1 (i) a stimulable phosphor sheet, PA1 (ii) an image recording means for exposing said stimulable phosphor sheet to a radiation passing through an object, thereby to store a radiation image of said object on said stimulable phosphor sheet, PA1 (iii) a read-out and erasing unit comprising, formed integrally with each other into a unit: (a) an image read-out means provided with a stimulating ray irradiation means for linearly irradiating stimulating ray to said stimulable phosphor sheet carrying said radiation image stored thereon, and a line sensor disposed along a position of exposure to said stimulating rays for photoelectrically detecting light emitted by said stimulable phosphor sheet in proportion to the stored radiation energy at said position of exposure to said stimulating rays, thereby to read out said radiation image, and (b) an erasing means for carrying out erasing by releasing radiation energy remaining on said stimulable phosphor sheet on which the image read-out has been finished, and PA1 (iv) a unit movement means for reciprocally moving said read-out and erasing unit in a direction approximately normal to the length direction of irradiation of said stimulating rays, PA1 (i) a stimulable phosphor sheet, PA1 (ii) an image recording means for exposing said stimulable phosphor sheet to a radiation passing through an object, thereby to store a radiation image of said object on said stimulable phosphor sheet, PA1 (iii) a read-out and erasing unit comprising, formed integrally with each other into a unit: (a) an image read-out means provided with a stimulating ray irradiation means for irradiating stimulating rays in a predetermined direction to said stimulable phosphor sheet carrying said radiation image stored thereon, and a photoelectric read-out means for photoelectrically detecting light emitted by said stimulable phosphor sheet in proportion to the stored radiation energy upon exposure to said stimulating rays and generating image signals, and (b) two erasing means disposed on either side of said image read-out means in a direction normal to the direction of irradiation of said stimulating rays for carrying out erasing by releasing radiation energy remaining on said stimulable phosphor sheet on which the image read-out has been finished, a light shielding means being provided between said image read-out means and said erasing means, and PA1 (iv) a unit movement means for reciprocally moving said read-out and erasing unit in a direction approximately normal to the length direction of iradiation of said stimulating rays,
whereby the recording material is efficiently circulated and reused.
The aforesaid radiation image recording and read-out apparatus is used very advantageously mainly for medical diagnosis, and it is increasingly desired in recent years to make the overall apparatus as small as possible. Specifically, in the case where the recording and read-out apparatus is large, the apparatus can be installed only at the center of a comparatively large-scale hospital. On the other hand, when the apparatus is made small, it can be installed in, for example, each medical examination room of a comparatively small-scale hospital, and thus the range of utilization of the apparatus can be expanded. However, the conventional radiation image recording and read-out apparatuses wherein the stimulable phosphor sheet is circulated and reused in the manner as mentioned above have not necessarily been proposed for making the overall apparatus small to such a high level. Thus some conventional radiation image recording and read-out apparatuses are still large as a whole and cannot satisfy the aforesaid need, and others require a circulation and movement means for the stimulable phosphor sheet and a movement means for sub-scanning in the course of image read-out and thus has the drawback that the internal movement mechanism becomes complicated as a whole.